There is previously known from U.S. Pat. No. 4,280,072 a motor with some features which exhibit similarity with the present invention. According to the embodiment shown in FIGS. 9 and 10 of said U.S. patent, an outer rotor part is used which comprises four inside-mounted magnets, each covering an angular range of 90.degree. of the entire circumference. The inside stator part comprises four components which are similar to cog rims, however these components do not comprise circumferentially uniformly distributed flux conducting elements or "fingers". There are two so-called "poles" on each component, each respective pole being divided into three "teeth", and each such pole range covers about 90.degree.. Three "teeth" extend in between three corresponding "teeth" on an oppositely facing component, and a corresponding set of two components are found right next to the first two components, with a 45.degree. shift in relation to the first set.
A serious question must be asked regarding the ability of the above mentioned motor regarding achieving a successively and uniformly increasing rpm from standstill to the desired rotation speed, due to the small number of magnets in the rotor part and the correspondingly small number of "poles" on the stator part, i.e. with only two "pole ranges" on each cog rim-like component. However, it appears from said U.S. patent that the electric machine primarily is a sort of asyncronous generator, so that the motor aspect is a secondary consideration, at least regarding the ability to provide a high torque. In the motor function, said U.S. patent attaches most importance to a smooth and "ripple"-free running. Besides, a main feature of said U.S. patent is that the angle between the "step intervals" in the "poles" on the stator part should not be equal to the angle between the magnet pole centers on the rotor part. This is an unfortunate feature regarding achieving a high torque.
From British patent application, publication no. 2,211,030 is previously known a stepper motor based upon some of the same principles as the present invention, but which as a starting point has a reversed construction, i.e. with the rotor placed in center and the stator on the outside. Thus, the motor is not directly usable in the manner mentioned in the first section of this specification. Besides, the construction of the flux-conducting elements in the stator part is more similar to an abandoned development stage of the the present invention, with axially inward bent fingers from annular plates conducting flux from the stator coils.